With the evolution of packet-based communications, any type of media may be provided in a packet-based form between any number of communication clients. The flexibility in interacting with various types of communication clients and services allows these communication clients to provide a significantly enhanced feature set over that commonly available over the traditional circuit-switched network. With packet-based multimedia sessions, multiple sessions of different media types can be associated with one another. Documents and files may be transferred in association with an existing audio or video conference. Streaming media may also be exchanged in association with such conferences or other telephony-based media sessions. Further, the communication clients may be implemented in various types of devices, including personal digital assistants and personal computers, in addition to telephony-focused devices. As such, not only do the communication clients often have the ability to handle different types of media sessions, they can provide greater processing capabilities for the information received via the media sessions.
Packet-based telephony has evolved to the point where communication sessions may be established in part over a packet network and in part over the circuit-switched network. When the circuit-switched network is involved, directory numbers are often used to establish at least a portion of the call that is established over the circuit-switched network. The directory numbers may be associated with the end device or with a gateway, which provides an interface between the circuit-switched network and the packet network that supports the communication client receiving the call. Unfortunately, end users have no automated way of determining whether the called party's communication client is a packet-based communication client or a traditional circuit-switched network telephone. As such, the end users typically have to establish a call and discuss the relative capabilities of their respective communication clients. If both communication clients have the ability to support telephony communications over a packet network as well as various multimedia capabilities, the users will exchange the addresses of their respective communication clients, such that a second call may be established to provide a packet-based media session therebetween.
In other situations, the called party's communication client may be multimedia capable, yet be affiliated with a circuit-switched network directory number. When a caller uses the directory number, the multimedia feature set may not be available or may be significantly limited. Further, if the call can be established entirely through the packet network, the number of resources used to route the call in part through the circuit-switched network is reduced. By reducing the transitions between a circuit-switched network and packet-based session or connection, the voice quality is not subject to as much degradation due to the delay, jitter, and conversions during the transitions from packet-based to Time Division Multiplexed (TDM) communications.
Accordingly, there is a need for a way in which the communication clients can automatically detect each other's capabilities and cause the existing telephony call to be established entirely through the packet network when both communication clients have such capabilities. There is a further need for the communication clients to automatically exchange their respective addresses and capabilities, such that sessions may be established between the communication clients in an efficient manner.